Used in a number of episodes of the show, it was descriptive of a non-specific illness, laying victims low by the thousand.

Probably because of the resonance and onomatopoeic nature of the word "lurgi" the phrase invaded the consciousness of the public, not only in the UK, but in many of the countries of the Commonwealth, so that it became virtually synonymous with suffering from a non-serious but misery-making affliction, such as the common cold, a stomach upset or whatever. Somewhat equivalent to the Australian phrase "I'm crook", you would be unlikely to take a case of the dreaded lurghi to the doctor, but you might well call in to work sick with it, and would certainly use it as an excuse for not having met social obligations.